A sensor of the known type comprises an excitation device for the optical excitation of a mechanical oscillation of the microresonator as well as a read-out device for detecting the oscillation of the microresonator. Such a sensor is known for example from the document WO 03/104767 A2. The sensor which is described there, may be used for the selective detection of gases, by way of a gas located in an environment of the microresonator being radiated with light of an absorption frequency of the gas, wherein this light is modulated with a resonant frequency of the microresonator. Thereby, the absorption frequency may correspond to an absorption spectral line of the gas, or, in the case of an upper-harmonic excitation, may correspond to an integer multiple of this. Absorption of this light by the gas then effects a pressure fluctuation with a time dependency corresponding to the resonant frequency of the microresonator, by which means the microresonator is excited into oscillation. Since thereby, an oscillation amplitude of the microprocessor depends significantly on whether and how greatly the gas in the environment of the microresonator absorbs light of the frequency or wavelength of the light used for the excitation, one may deduce a composition of the gas by way of a monitoring of an oscillation of the microresonator. With the state of the art from the mentioned document, the oscillation of the microresonator is detected by way of a piezovoltage produced by a movement of the microresonator being measured, thus the mechanical oscillation being converted into an electrical signal.
Disadvantageously, the described sensor therefore may not be applied in environments, in which an operation of electric apparatus may have harmful effects. This in particular concerns environments with strong electrical fields, explosive or easily ignitable media or environments which are sensitive for other reasons, for example in medical analysis arrangements.